The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Oct. 03, 1989
Filed:
Apr. 02, 1987
Alexander Wiertzfeld, Thanning, DE;
Roland Heinze, Ottobrunn, DE;
Siemens Aktiengesellschaft, Berlin and Munich, DE;
Abstract
A follower control matches the stimulation frequency of a heart pacemaker to patient load condition by obtaining measurement values S.sub.02 corresponding to the central venous blood oxygen saturation in the heart according to the principle of reflection oximetry, by forming control values B.sub.S1 according to the quotient .DELTA.S.sub.02 /.DELTA.S.sub.02max where the numerator is the difference between the current measurement value and a stored reference value (e.g. S.sub.02max or S.sub.02min) and the denominator serves to standardize the control value based on the maximum change of the measurement value over a relatively long time interval, and by changing the stimulation frequency by an amount dependent on the magnitude of the control value. Preferably, the stimulation frequency f.sub.p is set directly as a function of the control value B.sub.S1 and most preferably according to the function ##EQU1## where f.sub.min is a prescribed minimum frequency, .DELTA.f.sub.max is the maximum frequency difference, c.sub.w is a programmable constant and .DELTA.f.sub.opt is a frequency change introduced by a concurrently operating optimizing control. Artifacts are avoided by obtaining measurement values at sampling intervals distributed in the time span between heart beats and varying in phase during each measurement cycle, and then selecting the minimum measurement value occurring in each measurement cycle.